5 Techniques To Replace Servo System

- Nov 14, 2017-

5 Techniques To Replace Servo System

In many cases,we need servo products replacement solution,such as replacing a motor with a new servo motor.The reasons may

include:product scrap,cost savings,delivery time issues,or technical upgrades.There are a number of important factors that may need to be considered when it comes to the specific context of each application.In this article,we will try to briefly identify those most common factors,and the correct order of attention.

1.Healthy motivation

Regardless of the reasons why you need to replace a servo product,you must understand and keep in mind the top priority: reduce risk.A good replacement solution minimizes the potential problems that may arise during the upgrade.Without careful management of potential risks in the process of replacement,the probability of system failure increases.

Therefore,the cost should not be a decisive factor in the replacement program!A good replacement solution not only minimizes the risk but also reduces the system cost instead of reducing the cost but exposes the higher potential risk.

2.Shaft stability

Inertia matching is very important,but it is often overlooked.The replacement servo should have the same rotor inertia as the original servo,or as similar as possible.The goal is to maintain the stability of the system after install a new servo.Of course,the assumption here is that the original system has achieved the required stability.

If you are replacing a lower resolution system such as a tachometer,commutation encoder,or an older resolver system,can usually use a high resolution sine encoder with a resolution at least 220 lines per revolution (CPR) feedback equipment.Increase flexibility in matching rotor inertia.In general,when use a high-resolution device to improve the resolution of the feedback device,the inertia of the servo should be at least one-third of the original motor's inertia,and of course it is best to achieve half.This method has been successfully used in many fields application.

3.Speed and torque

Speed and torque matching are same important.Replacing motor performance should meet or exceed the performance of the original

motor.It is important to analyze both catalog parameter values(ie,continuous torque,rated speed)to ensure there are no defects.

The torque value must also be compared within the speed range of each motor.Comparing graphics is a very helpful way to compare the motor speed / torque curve and manually plot the desired value in a spreadsheet.For example,plot the continuous torque at 1000 PRM,Motor A = X Nm and Motor B = Y Nm,and perform the same operation over the entire speed range.

4.The motor size

Although the size is not particularly important for motor performance,the new servo motor can be used to help streamline operations if the new servo motor is installed in the same size as the original motor during replacement.The outline of the two motors should be analyzed to ensure consistency.It is a good idea to replace a motor that uses an industry standard base,such as NEMA or ICE.The relevant standards generally stipulate the same guide and bolt ring dimensions,while shaft dimensions are often not fixed.For example,you want to replace a NEMA 34 motor,the product definition by each manufacturer may vary widely!

5.Other factors

Is the machine the only part of the machine to be replaced? In general,changing a servo means replacing a servo drive,a servo

cable,and in some rare cases even having to replace a controller.In this case,the differences in motor windings can be a secondary consideration if the manufacturer's recommendations are followed.

However,if the replacement motor will work with the original servo motor controller,it should be carefully inspected.For example,the winding data (including motor constants: Kt and Ke),feedback device type and resolution,and cable pinout must be carefully checked and matched.In addition,different servo motor manufacturers often employ different units and conversion methods for these key parameters.This can make it difficult to clearly distinguish the definition and unit of the motor from the comparison.This article provides some useful additional information in this area,some of the common specifications that should be considered during servo change.

Other areas to compare include:overall envelope size,environmental index,fixed brakes,bearing and load life,and special  items.

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